A fiber optic connector within the field of this invention utilizes the precise dimensions of an alignment ferrule to accurately align an optical fiber therein with a mating fiber optic device. Typically, the ferrule will have a high precision front section that is concentric with a central passage in which the optical fiber is held, whereby orientation of the front section also orientates the corresponding optical fiber. A lower precision body portion is used to incorporate the ferrule into the fiber optic connector. These ferrules may be used either singularly or in conjunction with others.
Ferrules have been manufactured using a variety of methods to accommodate the high precision, and its associated costs, at the front section, while realizing cost savings through the lower precision requirements of the body portion. U.S. Pat. No. 4,634,214 discloses a two-piece ferrule where the front section is a cylindrical ceramic piece that is frictionally fit or bonded within a collar of a lower precision rear section.
U.S. Pat. No. 5,013,122 discloses a ferrule that is made from metal or thermoplastic material having the high precision front section and the body portion integrally formed. A bipartite ferrule may also be produced by attaching the front section to the rear body portion through the use of mechanical means, such as threads or bosses, or through bonding means, such as the use of heat, ultrasonic, or adhesive techniques.
Another ferrule, made from injection molded plastic, is disclosed in U.S. Pat. No. 4,834,487. This is a one piece ferrule that has a precision front section and a body portion formed such that the precision front section is free of molding flash.
The ferrules disclosed in the above patents have a number of drawbacks for high volume production. While the one piece ferrules have the necessary structural integrity, their production processes are limited by the high precision required at the front section. The two piece ferrules allow the manufacturing process and materials selection to be tailored to the particular sections of the ferrule, allowing for optimization of the manufacturing process. However, the two piece ferrules require joining features, such as threads, bores, or bosses, be incorporated. These additional features can impose the same precision requirements on the rear body section that were trying to be avoided.
What is needed is a ferrule that may be produced economically and in high quantities while taking advantage of the different precision and material requirements of the front section versus the rear body section, while still maintaining the precision required at the front section so that the optical fiber therein may be reliably coupled to the fiber optic device.